A wire mesh reinforcing is normally employed in concrete flat work. This mesh is supplied in rolls. It is made up of wire of a relatively heavy gage, e.g. four to ten gage. The mesh comprises longitudinal wires to which are welded cross wires forming a plurality of rectangles of, for example, 6 inch (15.24 centimeters) squares. A roll normally will be 5 feet (1.52 meters) long (axial length) and contain 150 lineal feet (45.72 meters) of mesh when unrolled. Such a roll made of six gage wire will weigh in the neighborhood of three hundred pounds. The size and gage of the mesh commonly used may be different in different parts of the country.
From the foregoing description of a roll of reinforcing mesh it will be apparent that these rolls are heavy and awkward to handle. What is not so apparent is that substantial problems and dangers are involved in unrolling the mesh at the location at which it is to be used. The rolls are tightly wound at the factory. To some extent they react like a tightly coiled spring, in that the various turns will suddenly unwind to a limited extent as the mesh is being unwound from the roll. A common practice is to unroll the mesh by workmen pushing the roll along the ground or other surface. The workmen must be very careful not to allow their fingers to project into the mesh as this unrolling proceeds, because when the sudden release of some of the outer turns occurs (as in the case of the expanding clock spring) fingers projecting into the mesh will be trapped by the turns rotating with respect to each other. This will result in serious damage to the fingers, and even the severance of fingers. Use of the present invention eliminates this danger to workmen.
Another problem encountered in the use of wire mesh is that of getting the mesh to lay flat. As the mesh is removed from the roll, the longitudinal wires retain a residual curvature, in the direction in which they were bent to form the roll. This residual curvature results in the mesh not laying flat. To get it to lay reasonably flat, it is necessary that the mesh be "backbend", i.e., the longitudinal wires bent in the reverse direction sufficiently to remove the residual curvature. This is, of course, time consuming and thus adds to the expense of the construction job. Furthermore, unless the backbending operation is carefully performed it may introduce even more unevenness into the mesh thus increasing the difficulty in getting the mesh to lay flat. Embodiments of the present invention will automatically backbend the mesh as it is unwound from the roll.
Concrete contractors use numerous items of power tools. Practically all of these items can be purchased as individual units, each powered by its own gasoline engine, such as a concrete saw, a surface grinder for concrete, a trencher, etc. Such units are not cheap and a contractor can find himself with a very substantial monetary investment in this type of equipment. This can be particularly a problem for the smaller contractors who are faced with the question of whether the labor saving achieved by each of these various units is sufficient to offset the fact that each unit will not be in constant use, so that capital is tied up in the unit even though the unit is standing idle a great deal of the time. Some smaller contractors attempt to avoid the problem by renting such power equipment when it is needed. While this avoids having capital tied up in idle equipment, the rental charges are relatively high.
The present invention provides a plurality of attachments which are usable alternatively on one of a power unit employed in connection with the unrolling of wire mesh. Since each of these attachments can be purchased by the contractor without the necessity for its own internal combustion engine, etc., the contractor's investment therein is greatly reduced. Thus, he is able to afford such a piece of power equipment even though it may not be used every day. There is the further advantage that each unit which embodies its own internal combustion engine, etc., is comparatively heavy and awkward to handle as compared to an attachment which does not embody an internal combustion engine. Furthermore, an internal combustion engine that is used only infrequently may not be in operable condition when it is required on the job. When the power unit is run every day with one attachment or another, the contractor knows that the engine is in operating condition.
One of the attachments previously mentioned is a concrete saw for cutting through the surface of a concrete slab. When this attachment is used on the power unit, the resulting structure has a number of features that are advantageous as compared to comparable conventional equipment. The conventional equipment has the saw out in front of the operator and the rotation of the saw is such that the removed concrete (primarily dust) is thrown by the saw back towards the operator. In the embodiment of the present invention, the saw blade directs the removed material away from the operator. In addition, a guide is provided between the operator and the saw blade which enables the operator to accurately guide the saw along the line of cut. Furthermore, this guide arrangement is an aid to the operator in avoiding the undesirable situation of having the saw blade twisted in the kerf made by the saw.
Other objects and advantages will be apparent from the following description taken in conjunction with the drawings.